12 AMERICAN JOURNAL 



cases, especially on old shells, are entirely obsolete. The inter- 

 nal margin is crenulated by a series of large teeth corresponding 

 with the external ribs ; anterior muscular scar enormously deep, 

 posterior not discernible on the internal casts. 



Measurements of two specimens : 



Length, 1-05 in., width from beak to base, -85 in., diameter 

 of two valves, '9 in. 



Length, -95 in., width from beak to base, '83 in., diameter 

 of two valves, -75 in. 



From the Jurassic of Volcano. I have also received a speci- 

 men labelled " Uniontown, 40 miles south-west of Austin, Reese 

 River, in the Union District." This is a deserted mining camp, 

 about ten miles south of lone. I found no fossils in this range, 

 nor could I learn, while on the spot, that any had ever been 

 discovered there. It is very probable that the shell was taken 

 there from the Volcano District. 



The present species is unlike any Cardium with which I am 

 acquainted. At first sight it has all the appearances of an un- 

 usually robust and heavily ribbed Area. On close examination, 

 however, it shows no signs of an area ; the cardinal margin is 

 rounded down at both ends, and on the internal cast the line' of 

 junction between the two valves is marked by an elevated ridge, 

 laterally undulated, showing the outline of the characteristic 

 teeth of the. genus to which I have referred the shell. 



ASTARTE, Sby. 



A. APPRESSA, Gabb. — PL 5, fig. 10. . 



Shell very flat, obliquely subquadrate ; beaks anterior, sub- 

 terminal, small ; anterior end nearly straight above, lower half 

 convex ; base and cardinal border equally convex, nearly paral- 

 lel ; posterior end broadly rounded ; cardinal margin truncated, 

 a narrow flat space, bordered by an angle running to near the 

 posterior end ; lunule long, narrow lanceolate, slightly impressed. 

 Surface ornamented by large, angular, concentric ribs near the 

 beaks, becoming less distinct and finally obsolete towards the 

 base. 



Length, l-l in. ; width, '9 in ; height of single valve, '12 in. 



Locality. With the preceding ; Mr. Clayton. 



This shell can be at once distinguished from A. ventricosa. 

 Meek, from the same formation, by its longer, quadrate outline 

 and flatter valves. The beaks of ventricosa are large, promi- 

 nent, and project beyond the cardinal margin ; while in the 



